This invention relates to bracing panels, their application and to methods of building utilising such bracing panels. The present invention also relates to studs, purlins, beams and other similar structural members.
Most building constructions, whether they are made of timber or metal, utilise slender elongate frame members connected together in end abutting relationship to form open perimeter or ladder type frames. Typically these frames include a series of spaced vertical studs extending between top and bottom plates. The connection between the studs and plates is generally not of the type which will permit moment transfer between the stud and plates to a sufficient degree to resist operational racking loads.
Accordingly such frames are not able to withstand racking loads without significant deflection. Typically these frames are braced with either internal or external structural panels such as plywood panels extending continuously between adjacent studs and top and bottom plates so as to stiffen the structure and provide it with the strength to withstand racking loads. Typically these are applied by wind loadings and offset vertical loadings.
While the use of plywood panels to provide the requisite strength and stiffness is widespread, the dynamic loads which may be applied by wind loadings and other loads frequently loosen the mechanical fastenings securing the plywood panel to the studs and plates and this severely weakens the structure. The provision of the plywood panels protruding from the common plane containing the aligned faces of the studs also creates problems in the application of the external cladding to the studs.
The present invention aims to provide an alternate structural member for use in bracing perimeter or ladder type frames.
The present invention in one aspect resides broadly in a structural member including a web portion having a plurality of substantially triangular cutouts, each of said cutouts is defined by a side edge portion displaced from the plane of the web portion and including an intermediate portion and a lip extending inwardly within the cutout.
In another aspect the invention broadly resides in a structural member including a web portion having a plurality of substantially triangular recesses, each of said recesses is defined by three intermediate portions and a floor portion positioned between the intermediate portions and displaced from the plane of the web portion.
The terms cutouts and recesses will hereinafter be referred to as recesses. The lip and the floor portion in a preferable form are stepped from the plane of the web portion. The web portion adjacent the cutout or recess, the intermediate portion and the lip or the floor portion preferably provide two discontinuities that impart rigidity to the structural member. The web portion adjacent the cutout or recess, the intermediate portion and the lip or the floor portion may form a substantially Z-shaped cross section. The Z-shaped cross section provides the structural member with additional stiffness and strength.
Each triangular recess may substantially be in the shape of an equilateral triangle. Each triangular recess may have three corner edge portions. Each corner edge portion is preferably bent at substantially right angles from the plane of the web portion. Each corner edge portion is preferably rounded or arcuate to prevent points of weakness from being formed.
The web portion in one embodiment includes one or more ribs formed in a non-apertured portion of the web portion preferably in the direction along the length of the structural member to provide additional stiffness. The web portion may have a checker plate configuration. This may restrict screw pullout.
The structural member is preferably a one piece member. The triangular recesses are preferably punched or pressed. The structural member is preferably made of light gauge metal. In one form the structural member is preferably formed from a light weight galvanized steel sheet.
The structural member in one form is a bracing panel and the recesses are arranged to provide continuous strut portions extending between opposed longitudinal edges of the panel. Preferably the arrangement of the recesses provides a plurality of continuous panel portions extending between the top and bottom edges of the panel, and strut portions extending between respective continuous panel portions. Suitably the strut portions are not in alignment across the web portion although they may be if so desired. Furthermore the strut portions may extend in one direction at one end of the panel and in the opposite direction at the opposite end of the panel.
In one embodiment there is a plurality of substantially triangular recesses or cutouts, each of the triangular cutouts or recesses form a substantially equilateral triangle, the cutouts or recesses are arranged in pairs with opposed side edges and each pair of cutouts or recesses are in the same orientation relative to adjacent cutout or recess pairs.
In another embodiment the triangular cutouts or recesses form a substantially equilateral triangle, the cutouts or recesses are arranged in pairs with opposed side edges and each pair of cutouts or recesses diagonally opposed to another pair of cutouts or recesses is orientated substantially 90 degrees relative to each other. With this arrangement of triangular recesses or cutouts a series of short diagonal struts joined to transverse extending portions or struts is formed and allows force directed along the diagonal struts to be readily dissipated thereby substantially avoiding a line of weakness from being formed within the panel.
There may be three to five vertical rows of triangular recess pairs depending on the width of the panel and the desired perimeter margin. The dimensions of the triangular recesses may vary between different panels. In one preferred embodiment of a bracing panel there are three vertical rows of triangular recess pairs wherein each triangular recess has side edge portions that are 89 mm in length.
The bracing panel may have one or more perimeter flanges. The perimeter flanges border the web portion. Preferably the perimeter flanges are formed as folded edge portions of the one piece structural member. Preferably there are attachment means that attach one or more of the perimeter flanges to adjacent supports such as vertical studs and top and bottom plates.
Suitably the flanges have returned free edge portions and preferably the lower flange is reinforced to permit the bracing panel to be through bolted to the bottom plate or building foundation such that in use, the bracing panel may extend upwardly therefrom in a cantilever manner so as to resist racking loads applied to the framing. Suitably, at least one edge of the panel is mechanically fastened to a stud and the upper edge of the panel is fastened to the top plate.
It is also preferred that the overall thickness of the panel at the flanges be less than the thickness of the framing with which the panel is to be used so that the bracing panel can be contained wholly within cladding applied to opposite faces of the framing.
The width of the bracing panel may vary depending on the spacing between the studs. In one embodiment the width of the bracing panel suitably permits fitting between studs with standard stud spacings.
In one preferred embodiment the panel may be fixed to the bottom flange by anchor bolts into the concrete foundations of bottom plate. The top flange may be bolted through the top plate with random nailing along the sides. The mounting to the concrete foundations or bottom plate may be supported by positioning of bolts or other suitable fasteners through one or more of the side flanges adjacent the bottom flange to the opposing stud or bottom plate.
In another form the structural member is a suitable support such as C-section members such as studs, Z-section members such as purlins, and box section members such as beams. In this form the triangular recesses are preferably positioned along one or more longitudinal rows whereby each recess is orientated at substantially 180 degrees relative to the adjacent recess.
In another aspect, this invention resides broadly in a method of bracing a framed structure including providing a bracing panel of the type variously described above, securing that panel between the top and bottom members of the perimeter frame.
Preferably the overall thickness of the bracing panel is less than the width/thickness of the frame members such that the bracing panel may be secured to the inner faces of the frame members inwardly from the opposed outer edges thereof.
It is also preferred that at least one longitudinal edge of the bracing panel be mechanically fastened to the internal face of an adjacent one of the stud members which forms the perimeter frame.
In another aspect, this invention resides broadly in a method of forming a structural member as described above including:
providing feedstock of sheet metal;
feeding the sheet metal to a forming station;
forming triangular recesses as described above and forming a desired recess arrangement in the sheet metal, the recesses being punched or pressed so as to have a side edge portion displaced from the plane of the web portion and including an intermediate portion and a lip extending inwardly within the cutout; and
folding peripheral edge portions of the sheet to form peripheral flanges.
In yet another aspect this invention resides broadly in a building method including forming a circumferentially flanged rectangular bracing panel from sheet metal;
locating the bracing panel within an opening formed between studs and top and bottom plates;
bolting the lower flange of the bracing panel to the bottom plate and any foundation member there beneath, and
securing the remaining flanges to the adjacent studs and top plate, and
applying cladding to opposite faces of the studs and plates so as to enclose the bracing panel there between.
The panel web portion of the bracing panel may be substantially planar but preferably the bracing panel is of a form as variously described above.
Preferably the recesses have edges that are folded to provide additional strength and stiffness to prevent fatigue and tearing. Preferably the folded sections extend substantially inwardly. Preferably the folded sections fold along each side of the recess. The folded section may include an inwardly extending portion and a return flange which may extend substantially parallel to the panel web portion. Preferably the comers of the recesses are arcuate or rounded to prevent points of weakness from being formed and dissipate stress forces.
The shape of the recess provides the panel and structural member with additional strength and stiffness. As well the arrangement of the recesses relative to each other as described herein provides the panel and structural member with additional strength against torsional forces and racking loads.